Carrier composition

Abstract

A carrier particle for an electrostatographic process, and a developer employing such carrier particle, is provided. The carrier particle includes an irregular shaped ferrite core, and a coating applied to the core. The developer includes a carrier particle comprising the irregular shaped ferrite core and a toner. The irregular shaped ferrite cores and developers exhibit reduced toner aging and/or reduced material performance degradation, while exhibiting excellent triboelectric and conductive properties.

1 . A carrier composition for an electrostatographic process, the carrier composition comprising: 
 an irregular shaped ferrite core; and    a coating applied to said irregular shaped ferrite core.    
     
     
         2 . A carrier composition according to  claim 1 , wherein the coating is present in an amount of about 0.4% by weight to about 1.0% by weight of the carrier.  
     
     
         3 . A carrier composition according to  claim 1 , wherein the coating is present in an amount of about 0.4% by weight to about 0.8% by weight of the carrier.  
     
     
         4 . A carrier composition according to  claim 1 , wherein the irregular shaped ferrite core comprises a metal oxide selected from the group of oxides consisting of iron, calcium, magnesium, lithium, manganese, and titanium.  
     
     
         5 . A process for preparing a carrier particle with a substantially stable conductivity parameter, the process comprising: 
 providing an irregular shaped ferrite carrier core and a coating material;    dry mixing the irregular shaped ferrite core with the coating material so that the coating material adheres to the irregular shaped ferrite core;    heating the mixture of irregular shaped ferrite core and coating material to a temperature of from about 350° F. to about 450° F.; and    cooling the coated carrier particle.    
     
     
         6 . The process according to  claim 5 , wherein the mixture of the irregular shaped ferrite core and coating material is heated to a temperature of about 450° F.  
     
     
         7 . A developer composition comprising: 
 a carrier particle comprising i) an irregular shaped ferrite core and ii) a coating material applied to said irregular ferrite core; and,    a toner composition.    
     
     
         8 . A developer composition according to  claim 7 , wherein the coating material is present in an amount of from about 0.4% by weight to 1.0% by weight of the carrier particle.  
     
     
         9 . A developer composition according to  claim 7 , wherein the coating material is present in an amount of from about 0.4% by weight to about 0.8% by weight of the carrier particle.  
     
     
         10 . A developer composition according to  claim 7 , wherein the irregular shaped ferrite core comprises a metal oxide selected from the group consisting of iron oxide, calcium oxide, magnesium oxide, lithium oxide, manganese oxide and titanium oxide.  
     
     
         11 . A process for forming a display, said process comprising: 
 generating an electrostatic latent image on an imaging member; and,    developing the latent image by contacting the imaging member with a developer composition, wherein the developer composition comprises i) a carrier particle comprising a irregular shaped ferrite core and a coating material; and, ii) at least one toner particle attached to the carrier particle.    
     
     
         12 . The process of  claim 11 , wherein the toner particle is present in the amount of about 2 percent to about 6 percent by weight of the developer composition.  
     
     
         13 . The process of  claim 11 , wherein the coating material includes a polymer to control toner charge.  
     
     
         14 . The process of  claim 11 , wherein the toner particle includes a colorant in a resin binder.  
     
     
         15 . The process of  claim 11 , wherein the toner particle also includes an additive selected from the group consisting of a charge control agent, surface additives to control flow or clearing, and a wax to control toner particle adhesion.  
     
     
         16 . The process of  claim 11 , wherein the irregular shaped ferrite core comprises a metal oxide selected from the group of iron oxide, calcium oxide, magnesium oxide, lithium oxide, manganese oxide and titanium oxide.